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On startup Firefox says "couldn't load XPCOM"


My desktop is running Windows 8, which recently crashed. Since then, every time I start up, Firefox 17.1 (which is in the startuo folder) does not load, but brings up an error window saying (Couldn't load XPCOM). Dismissing the window then allows me to start Firefox myself. I have uninstalled Firefox (but not the personal stuff), downloaded a new copy of Firefox 17.1 and re-installed.... same thing happens.

Just to clarify ..... this only happens once, following the initial boot up of the desktop. I dismiss the error window and all is well after that.

Any bright ideas please?

What is XPCOM referring to? A missing dll file? can I find this file elsewhere and move it to the correct location?

Many regards.

Chosen solution

Thanks again for all the responses. I have now put Firefox back into my Windows 8 startup folder and rebooted. All is fine, Firefox (and Thunderbird) starts as it is supposed to and there is no sign of an XPCOM related error message! So .... I would have to assume that the problem was (somehow) caused by the crashing of my Windows 8 and that (somehow) removing Firefox from the Win 8 startup folder, rebooting, then putting Firefox back into the startup folder, and then rebooting, has put things back where they used to be. Somewhat strange, but hopefully the above may be of use to someone else with a similar problem in the future. Many regards to all.

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Additional System Details

Installed Plug-ins

  • Shockwave Flash 11.5 r502
  • The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • Next Generation Java Plug-in 10.9.2 for Mozilla browsers
  • NPRuntime Script Plug-in Library for Java(TM) Deploy
  • Google Update
  • iTunes Detector Plug-in
  • Adobe PDF Plug-In For Firefox and Netscape 11.0.0
  • Picasa plugin
  • 5.1.10411.0
  • The plug-in allows you to open and edit files using Microsoft Office applications
  • Office Authorization plug-in for NPAPI browsers


  • User Agent: Mozilla/5.0 (Windows NT 6.2; rv:17.0) Gecko/20100101 Firefox/17.0

More Information

Firefox 17.1
Windows 8

J_K_H_Friedge 0 solutions 5 answers

I'm using FF 21.0 and I've tried a new start right now - the message is GONE?? ( but there is also no XUL.dll only a file "ffjcext.xul"?) I think we have to realize that we know nothing ;=) eot for me.